The debate surrounding the impact of farmed salmon on wild salmon populations often focuses on the issue of sea lice.
Wild salmon supporters correlate the decline of wild fish to the sea lice harboured on fish farms, a theory refuted by the farms due to the lack of directly supporting scientific evidence.
It is true that there is no unequivocal evidence to show a salmon farm sea louse leaving a farm, attaching to a wild salmon juvenile and then seeing that fish die as a direct result of weakness and infection caused by the louse. However, what independent scientists do see is that when wild juvenile salmon leave their spawning grounds they have no parasites, and when they approach the farms they are inundated with sea lice. Later many of these fish die.
The argument surrounding sea lice is like so many difficult environmental debates we are now facing. Because the ecosystems we live in are so large and so complex, it is often virtually impossible to find direct scientific correlations between cause and effect.
Instead we must look at the weight of evidence to support one argument versus the other.
In the example of air pollution we do not have specific evidence that pollutants released by one individual factory lead to breathing problems. However it has been accepted that the cumulative worsening of air quality is harmful to human health. Therefore we protect ourselves and limit emissions.
Sea lice incubated by farms are not the only cause for depletion of wild salmon stocks, but they are a significant factor.
It is likely that wild fish will be long gone before we find undeniable evidence of the link between open-net fish farms and the disappearance of wild salmon. We need to act in good faith with the weight of evidence we have available to us now.
We are appealing to the press to bring this serious issue in to the election debate and ask each candidate to support moving fish farms to closed containment, away from our wild salmon.
President of the Wilderness Tourism Association